Directly connected magnetron powered self starting plasma plume igniter

Abstract

An igniter for use in aircraft gas turbine and rocket engines that derives its energy from a directly connected magnetron. The igniter is intended to be mounted exterior of the engine, and to protrude into the engine's combustion chamber. The magnetron energy is conductively connected to one end of a coaxial transmission line. The other end of the transmission line is at a region of high potential, and there is a small gap between the inner and outer transmission line conductors in that region. A gas comprised of either an oxidizer or fuel is flowed past the gap, and into the combustion chamber of the engine. The high potential causes a plasma to be formed in the gas, which plumes into the combustion chamber and ignites the propellants flowing therein. In another embodiment disclosed, instead of the plasma flowing directly into the combustion chamber after creation, it flows for a short distance in a pre-burner section of the igniter where fuel is added in the case of an oxidizer plasma, or oxidizer is added in the case of a fuel plasma. In either case, a flaming mixture is created which is then injected into the combustion chamber to ignite the propellants. Both straight through embodiments and embodiments having a right angle bend in the transmission line are disclosed.

Description

BACKGROUND OF THE INVENTION

[0001] Turbojet, turbofan, and rocket engines of current design are generally started using spark discharge igniters that protrude into the engine's combustion chamber, or into a precombustion chamber and ignition flame tube, as in the Space Shuttle main rocket engine. A commonly used igniter type employs a high voltage source (several tens of kilovolts) which is repeatedly discharged across a gap in a manner similar to ordinary automobile spark plugs. One particular design of this type is called a cavity type plasma jet igniter. The spark plugs used with this type system have a small cavity integrated into the region where the electrodes are located. When fired, the arc discharge ejects or puffs-out a heated volume of gas through an orifice in the cavity into the fuel / air mixture, the heated volume including a plasma filament.

[0002] Variations of this type of plug, in combination with surface discharge spark initiation features, have become widely used ...

Images